Palestinian fishermen collect their catch at the seaport of Gaza City early morning September 26, 2016. Picture taken September 26, 2016. REUTERS/Mohammed Salem

Get access to the best calls on Wall Street with StreetInsider.com's Ratings Insider Elite. Get your Free Trial here.

By Nidal al-Mughrabi

GAZA (Reuters) - When Palestinian fisherman Abu Mohammed came under pressure to become an informer for Israeli intelligence, the 45-year-old father of five took a radical decision - he quit fishing and became a builder.

Working off the coast of Gaza, where Israel imposes restrictions preventing fishing boats going out more than six nautical miles, was already hard enough without Israel's security services trying to co-opt him, he said.

According to the Al-Mezan Association, a Palestinian human rights group, 113 Gaza fishermen have been detained by Israel this year, compared with 41 in the same period of 2015. Those detained say there is also increased pressure - including the threat of losing their boats - to divulge information that might help Israel's security services.

Gaza is run by Hamas, an Islamist group whose founding charter calls for Israel's destruction. One of the reasons Israel maintains such tight restrictions on Gaza's water is to prevent the smuggling of weapons by militant groups.

The Israeli naval commander overseeing Gaza's coast confirmed around 70 fishermen have been detained this year. They were handed over to the Shin Bet intelligence agency or other bodies for questioning before being returned to Gaza, he said.

"Our job is to look out for the enemy, having to deal with fishermen is a distraction for the forces," said the commander, who gave his name simply as Captain Guy. "We want them to make a living and we want to protect our vital interests."

The Shin Bet did not respond to a request for comment.

For Abu Mohammed and others, most of whose lifetime has been spent at sea, the experience has left a lasting scar.

"I was on the boat with relatives and friends when an Israeli naval vessel came close," he said, describing events earlier this year and declining to give his full name for fear of reprisals.

"They fired at the boat and hit it, we stopped and they arrested us. They blindfolded us on the boat, tied our hands and took us for interrogation at a base in Ashkelon," he said, referring to a nearby Israeli city.

There an Israeli security officer asked him for information about militants in his neighborhood and said he would give him a chance to think. "In three days I will call you and I hope you cooperate," he says the officer told him.

Scared and confused, Abu Mohammed says that when he was returned to Gaza he broke his phone's SIM card, handed himself over to a local security service and was unemployed for several months before joining friends in construction. "I preferred to starve rather than become a spy," he said.

OVER-FISHED

While there are around 4,000 fishermen in Gaza, making it one of the largest employers in the strip of 1.9 million people, only 500-700 fish regularly, either because business is too tough or they fear being detained.

Under an interim peace deal, Gaza's fishermen were supposed to be allowed to trawl 20 nautical miles off the coast. But after Hamas seized control in 2007 following a brief civil war with rival Palestinian group Fatah, a range of three and sometimes six nautical miles was enforced.

There have been periods of relaxation since, but for most of the past decade, the limit has remained the same, meaning the waters have become over-fished and depleted. Gaza now imports spawn from Israel and farms fish.

"The past year is the worst, maybe not only in the past 10 years but in a 100 years," said Majed Abu Reyala, 41, who became a fisherman at the age of seven.

"I have been in debt for the past four months, there is no work," he said. "It is not safe, someone who goes into the sea does not know whether he will make it out safely."

Hisham Baker, chairman of Gaza's fishermen, said Israel's restrictions and what he called its blackmail had reached an unprecedented scale, putting the profession in danger.

"Many fishermen have quit," he said. "And we are afraid many others may follow."

(Reporting by Nidal Almughrabi in Gaza and Ori Lewis in Jerusalem Editing by Jeremy Gaunt)